Nsk Corporation

Hirokazu Abe

Yoshiki Ninomiya

Toru Sakaguchi

Kazuhiro Kumaido

Yasuhide Nomura

An electric power steering apparatus includes a steering torque detector for detecting a steering torque applied to a steering mechanism, a motor for generating an assist force that assists steering of a steering wheel, a power voltage detector for detecting a power voltage of a power supply, a power voltage monitoring section for determining a power voltage detection value detected by the power voltage detector and a motor drive controller for calculating an assist amount based on the steering torque and controlling drive of the motor through a driving section. Assist control is maintained based on a drive possible characteristic corresponding to a reduction level of the power voltage of FETs when the power voltage monitoring section determines that the power voltage detection value is less than or equal to an assist operation possible power voltage.

Electric power steering apparatus

[Problem] An object of the present invention is to provide a power state diagnosis method and a power state diagnosis apparatus that pass and increase not only a d-axis current but also a q-axis current to a current value that a steering behavior does not occur to perform a diagnosis in the vector control of a motor, and determine that a power supply degraded, that the power supply is normal and that the diagnosis is not completed without giving an uncomfortable feeling to a driver, detecting a timing that there is not a driver, and needing to comprise a plurality of actuators. [Means for solving the problem] The present invention is a power state diagnosis method that diagnoses a power state of a vehicle which comprises an electrical control system supplied from a power supply and a motor controlled by a vector control method, comprising: gradually increasing a d-axis current to a current value that a steering behavior does not occur and applying the d-axis current, concurrently gradually increasing a q-axis current that is a rectangular-wave with positive and negative directions to the current value and applying the q-axis current, and determining degradation of the power supply when a voltage value of the power supply is equal to or less than a power supply threshold and a given period of time Telapses.

Power state diagnosis method and apparatus

An electric power steering device comprising a control unit capable of distinguishing a failure of a motor current detection device caused by a change in power voltage, an oxide film formed on the commutator of a motor or the contact point of a relay, etc. from a failure of the motor current detection device itself and judging a failure of the motor current detection device accurately. A motor current is sampled during which a predetermined constant voltage is supplied to the motor, and the detected motor current value is compared with a motor current estimated value to judge the failure of the motor current detection device.

Growing community of inventors

Maebashi, Japan

Hirokazu Abe